New Technology May Soon Introduce White Blood Cell Counts to Point-of-Care

A blood sample treated with a new dye assay flows through a microfluidic channel (lower left). The sample’s fluorescence enables a count of the four major subtypes of white blood cells (upper right) within the blood.

Today’s white blood cell counters (WBC) are bulky machines that often require large blood samples and can take hours for a simple output. Furthermore, differential WBC count is often done manually, by a human being, so the results can take a day or so.

Researchers from Caltech and Jerusalem, Israel-based LeukoDx seem to be on the right track having developed a prototype WBC system that uses only 5 μL of blood and spits out results in minutes. It’s currently the size of a briefcase, but the team claims it could be made much smaller. The device counts all five white blood cell subtypes and provides a differential on the four most common ones. Purportedly it can also detect very high levels of the fifth, basophil granulocytes, which is normally quite rare in blood and hard to detect.

More details about the technology inside from a Caltech announcement:

The heart of the new device is a 50-micrometer-long transparent channel made out of a silicone material with a cross section of only 32 micrometers by 28 micrometers—small enough to ensure that only one white blood cell at a time can flow through the detection region. The stained blood sample flows through this microfluidic channel to the detection region, where it is illuminated with a laser, causing it to fluoresce. The resulting emission of the sample is then split by a mirror into two beams, representing the green and red fluorescence.

Thanks to the dye assay, the white blood cell subtypes emit characteristic amounts of red and green light. Therefore, by determining the intensity of the emissions for each detected cell, the device can generate highly accurate differential white blood cell counts.

Study in Lab on a Chip: Four-part leukocyte differential count based on sheathless microflow cytometer and fluorescent dye assay

Press release: Counting White Blood Cells at Home